1. Field of the Invention
This invention relates to a semiconductor device with an MIM capacitor and a method of fabricating the same.
2. Description of Related Art
In conventional semiconductor devices, aluminum (Al) wirings are usually employed as metal wirings for electrically connecting between elements formed on a silicon substrate. An Al film deposited on an insulating film is patterned by photolithography and anisotropic etching processes. However, as devices and wirings are more miniaturized, It becomes to be difficult to not only form low resistance wirings but also pattern the Al film by anisotropic etching or bury an insulating film at the space between the wirings. From these viewpoints, there has been provided a cupper (Cu) wiring technique with a damascene process for forming metal wirings in place of Al wirings.
On the other hand, capacitors are indispensable for an LSI in which analog circuits are integrated. In general, as an analog circuit-use capacitor, an MIM (Metal-Insulator-Metal) capacitor, which may be statically formed with a large capacitance, is used. Since the MIM capacitor is formed to have top and bottom metal electrodes, its forming process may be partially shared with a Cu multi-layer wiring forming process with a damascene process. There has already been provided various process techniques for coexisting MIM capacitors and Cu damascene wirings (refer to, for example, Japanese Patent Application Laid Open (kokai) No. 2002-270769).
In a case that an analog circuit with an MIM capacitor serves as a high-frequency circuit, in order to achieve high-speed performance by preventing transmitted signals from deterioration, it is required to possibly decrease capacitances between multi-layer wirings, and use an interlayer insulating film with a low dielectric constant for the purpose. However, low dielectric constant insulating films are generally inferior in step-coverage. To improve the step-coverage of the insulating film covering the MIM capacitor, it is effective to use a film deposition method with a high-density plasma (HDP)-type CVD apparatus. However, the insulating film deposited by the above-described method is in general in high water-absorbability and high thermal contractibility. These properties cause the contact between the insulating film and metal films or the like to be deteriorated, thereby easily resulting that the metal corrosion and peeling of the film are brought.
Therefore, it is not easy to achieve high reliability of the MIM capacitor which is integrated on a semiconductor device with Cu multi-layer interconnections.